It is surprising that a relatively commonplace plumbing fitting, such as a diverter valve that permits water to flow either from a faucet or from a hand spray in a household or commercial sink arrangement must satisfy a number of conflicting and quite important demands. Illustratively, diverter valves of this nature must completely terminate the flow of water from the spout when flow is desired from the hand spray. To achieve this relatively commonplace goal, rather large diverter valves that are expensive and difficult to install have been required. Smaller valves, in contrast, nevertheless permit water to flow from spouts during hand operation generally because the smaller sizes of the seals in the pilot valves that divert the water flow do not permit forces of sufficient magnitude to be developed to completely seat the seal within the valve. As a consequence, these valves tend to "stick" in a partially open condition that fails to terminate flow from the spout.
The diverter valve, moreover, aside from its function as an item of modern plumbing equipment, also must prevent absolutely the reverse flow of impure or contaminated water into a municipal fresh water distribution system. For example, if the spray valve is, for some reason, kept open and the spray nozzle is immersed in contaminated water, this contaminated water will be drawn into the municipal water supply if that supply is subjected to a vacuum or a negative pressure. This is not a particularly remote possibility.
The combination of a spray valve jammed in an open position while the spray nozzle is submerged in dishwater at the same time that fire-fighting requirements are producing a negative pressure or vacuum in the municipal water distribution system is not at all far-fetched in view of the large number of spray and faucet combinations that are likely to be found in any community within the United States sharing a common water supply. The danger to public health that contamination of this nature will cause is almost self-evident and every possible effort must be made to avoid such a hazard.
Through the years there have been a number of proposals to reconcile these diverse and somewhat conflicting diverter valve requirements in a device that not only enjoys a long and maintenance-free life, but also uses few parts and is available at a competitive price. These proposals, however, failed to satisfy all of these needs in the same device. Illustrative of these proposals are the following United States patents:
U.S. Pat. No. 2,939,474, granted to B. J. De Simone et al on June 7, 1960 for "Portable Diverter Valve" shows one of the large, cumbersome devices that are attached to the end of a spout, rather than concealed within the fitting structure.
U.S. Pat. No. 3,232,307, granted to E. H. Bucknell et al on Feb. 1, 1966 for "Transfer Valve" also discloses another large and cumbersome apparatus.
U.S. Pat. No. 3,336,935, granted to I. A. Ward et al on Aug. 22, 1967 for "Diverter" also described another cumbersome and bulky valve structure.
U.S. Pat. No. 3,376,884, granted to E. H. Bucknell et al on Apr. 9, 1968 for "Anti-Siphon Diverter Unit" also fails to satisfy industrial and consumer needs for the same reason as the '935 patent mentioned above.
U.S. Pat. No. 3,433,264, granted to R. G. Parkison on Mar. 18, 1969 for "Noise Reduction Structure For Mixing Valve" describes a faucet fitting, but does not disclose a diverter valve function.
U.S. Pat. No. 3,459,207, granted to K. G. Bacheller on Aug. 5, 1969 for "Faucet Construction" also describes another large and bulky diverter valve.
U.S. Pat. No. 3,754,709, granted to K. A. Laatsch on Aug. 28, 1973 for "Hose Nozzle With Discharge Control" describes an apparatus that also fails to satisfy the need for a small, compact diverter valve.
U.S. Pat. No. 3,895,643, granted to I. A. Ward on July 22, 1975 for "Valve Assembly" describes still another bulky and difficult to install diverter valve.
U.S. Pat. No. 3,906,983, granted to R. G. Parkison on Sept. 23, 1975 for "Diverter Valve" shows an apparatus that requires manual operation in contrast to a more desirable reliance upon an application of hydraulic forces to produce the necessary diverter valve operation.